As the space shuttle prepares to return to orbit, NASA is already thinking about Mars and moon missions, handing out contracts yesterday to companies designing vehicles to reach the planets.

But, though its vision might be bold, during the past 20 years NASA has lost much of its luster – and much of the market it once held exclusively to create business opportunities in space. That’s primarily because the shuttle proved to be the very two things ardent government promoters promised it would not be: unreliable and expensive.

Now NASA faces competition from at least a dozen private companies that have built up an industry estimated to be $100 billion, offering everything from launch services to lunch in space.

“The giggle factor has gone away,” Joe Huwaldt, the chief engineer for Oklahoma City-based Rocketplane Limited Inc., said yesterday. “When we say to people we can do this, they don’t laugh anymore.”